The invention is directed to a means for feeding wire, cutting and forming it to provide a jumper bridge for an electronic, hybrid circuit board substrate, and delivering the jumper bridge to a pick-up position for application to the substrate.
Hybrid circuits are a combination of discrete and integrated circuit techniques. As in integrated circuits, conductors, resistors and conductive lands are printed on a ceramic substrate. In thick film technology, the printed elements are generally several mils thick. Then discrete chips are precisely positioned over the conductive lands and subsequently bonded in position in a manner to complete the electrical circuit. The printed conductor lands provide a pattern which precisely matches to the solder bumps on the bottom surface of the flip chip and these bumps connect to the circuit elements within the chip. The bonded chips and substrate, with an exposed lead frame, are frequently encapsulated in toto in a potting compound for protection against physical and environmental damage. Use of unencapsulated chips on the circuit board allows for the manufacture of physically smaller circuits than those where discrete components which have already been encapsulated have their leads inserted into circuit boards fitted with receiving connectors or into predrilled holes wherein the leads are subsequently cut and clinched. A primary advantage of chips is their small size, some being nearly microscopic. Chips in the order of 0.030 by 0.030 inches square and 0.010 thick and solder bumps and conductor lands in the order of 0.005 inches in height and width, and spaced apart by similar distances, are not uncommon.
Frequently, due to the dense population of these hybrid components on a substrate of small size and in order to complete a specific electrical path without shorting out various other portions of the circuit, it is necessary to provide small jumper bridges between the specific electrical points of the printed circuit.
In the past, these jumper bridges have been formed, placed, and connected by hand. Accordingly, it is an object of the instant invention to provide a machine by which wire stock (preferably rectangular in cross-section) may be fed from a semi-continuous supply such as a reel, cut and formed into an appropriate sized jumper bridge, and delivered to a pick-up station for removal and placement of the jumper bridge onto the substrate. At the pick-up or removal station, an apparatus such as that disclosed in U.S. Pat. No. 4,151,945 may be used for the removal and placement of the jumper bridge.
It is a further object of the invention to provide such a machine which is relatively inexpensive and simple in design, as well as compact enough to be easily incorporated into a machine for hybrid circuit board population, so the machine may be controlled automatically by a computer or the like through valve actuation signals.
Briefly, a housing contains fixed and horizontally reciprocatable cam gripper assemblies for gripping wire stock which is fed longitudinally from rear to front of the machine. On the front of the machine is a unique cutter and former means, part of which reciprocates vertically. The other portion of the cutter and former is a reciprocatable wire guide which longitudinally supports and guides the wire stock prior to cutting and forming thereof, and which also delivers the formed jumper bridge to a removal station in an appropriate orientation for pick-up. The various horizontally and vertically reciprocatable parts of the machine are actuated by a piston and cylinder controlled driver during portions of the forward and reverse strokes.
The specific nature of the invention as well as other objects, features, and advantages and uses thereof will become apparent from the following detailed description of the preferred embodiment taken in conjunction with the accompanying drawings.